#define _CRT_SECURE_NO_WARNINGS 1

#include "string.h"
namespace string
{
	const size_t string::npos = -1;

	string::iterater string::being()
	{
		return _str;
	}
	string::iterater string::end()
	{
		return _str + _size;
	}
	string::iterater string::begin() const
	{
		return _str;
	}
	string::iterater string::end() const
	{
		return _str + _size;
	}

	string::string(const char* str)
	{
		_size = strlen(str);
		_str = new char[_size + 1];
		_capacity = _size;
		strcpy(_str, str);
	}
	string::string(const string& s)
	{
		_str = new char[s._capacity + 1];
		strcpy(_str, s._str);
		_size = s._size;
		_capacity = s._capacity;
	}
	string& string::operator=(const string& s)
	{
		if (this != &s)
		{
			char* tmp = new char[s._capacity + 1];
			strcpy(tmp, s._str);
			delete[] _str;

			_str = tmp;
			_capacity = s._capacity;
			_size = s._size;
		}

		return *this;
	}
	string::~string()
	{
		delete[] _str;
		_str = nullptr;
		_size = _capacity = 0;
	}

	const char* string:: c_str() const
	{
		return _str;
	}

	size_t string::size() const
	{
		return _size;
	}
	char& string::operator[](size_t pos)
	{
		return _str[pos];
	}
	const char& string::operator[](size_t pos) const
	{
		return _str[pos];
	}

	void string::reserve(size_t n)
	{
		if (n > _capacity)
		{
			char* tmp = new char[n + 1];
			strcpy(tmp, _str);

			delete[] _str;

			_str = tmp;
			_capacity = n;
		}
	}

	void string::push_back(char ch)
	{
		if (_capacity == _size)
		{
			size_t newcapcity = _capacity == 0 ? 4 : _capacity * 2;
			reserve(newcapcity);
		}

		_str[_size] = ch;
		_str[_size + 1] = '\0';

		_size++;
	}
	void string::append(const char* str)
	{
		size_t len = strlen(str);
		if (len + _size > _capacity)
		{
			reserve(len + _size);
		}

		strcpy(_str + _size, str);
		_size += len;
	}

	string& string::operator+=(char ch)
	{
		push_back(ch);
		return *this;
	}
	string& string::operator+=(const char* str)
	{
		append(str);
		return *this;
	}

	void string::insert(size_t pos, char ch)
	{
		if (_capacity == _size)
		{
			size_t newcapcity = _capacity == 0 ? 4 : _capacity * 2;
			reserve(newcapcity);
		}

		int end = _size + 1;
		while (end > (int)pos)
		{
			_str[end] = _str[end - 1];
			--end;
		}

		_str[pos] = ch;
		_size++;
	}
	void string::insert(size_t pos, const char* str)
	{
		size_t len = strlen(str);
		if (len + _size > _capacity)
		{
			reserve(len + _size);
		}

		int end = _size + len;
		while (end > pos + len - 1)
		{
			_str[end] = _str[end - len];
			--end;
		}

		memcpy(_str + pos, str, len);
		_size += len;
	}
	void string::erase(size_t pos, size_t len)
	{
		if (len > _size - pos)
		{
			_str[pos] = '\0';
			_size = pos;
		}
		else
		{
			for (int i = pos; i < len; ++i)
			{
				strcpy(_str + pos, _str + pos + len);
				_size -= len;
			}
		}
	}

	size_t string::find(char ch, size_t pos)
	{
		for (int i = pos; i < _size; ++i)
		{
			if (_str[i] == ch)
			{
				return i;
			}
		}

		return npos;
	}
	size_t string::find(const char* str, size_t pos)
	{
		char* sub = strstr(_str + pos, str);

		return sub - _str;
	}

	void string::swap(string& s)
	{
		std::swap(_str, s._str);
		std::swap(_capacity, s._capacity);
		std::swap(_size, s._size);
		
	}
	string string::substr(size_t pos , size_t len)
	{
		if (len > pos + _size)
		{
			string sub(_str + pos);
			return sub;
		}
		else
		{
			string sub;
			sub.reserve(len);
			for (int i = 0; i < len; ++i)
			{
				sub += _str[pos];
			}

			return sub;
		}
	}

	void string::clear()
	{
		_str[0] = '\0';
		_size = 0;
	}

	istream& operator>>(istream& is, string& str)
	{
		str.clear();
		char ch = is.get();
		while (ch != ' ' && ch != '\n')
		{
			str += ch;
			ch = is.get();
		}

		return is;
	}
	ostream& operator<<(ostream& os, string& str)
	{
		for (int i = 0; i < str.size(); ++i)
		{
			os << str[i];
		}
		return os;
	}
}